use warnings;
use strict;
use Tk;

my %w;

$w{size} = 90;

$w{mw} = MainWindow->new;

$w{mw}->Label( -text => 'Let it snow!' )->pack;

$w{frame} = $w{mw}->Frame(-borderwidth => 10)->pack;

$w{scale} = $w{frame}->Scale(qw/-orient vertical -length 284 -from 120 -to 10 /,
    -command => sub { $w{label}->configure( -font => "{Arial} $w{size}") },
    -variable => \$w{size}
)->pack(-side =>'left');

$w{label} = $w{frame}->Label(
    -text => "\x{2603}",
    -font => "{Arial} $w{size}"
)->pack(-side =>'right');

$w{frame}->Button(
   -text => "${_}pt.",
   -width => 4,
   -command => [ sub { $w{scale}->set($_[0]) }, $_ ]
)->pack() for qw/20 40 60 80 120/;

MainLoop;

##</code><code>##

[ sub { $w{size} = $_[0] }, $_ ]